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Musculoskeletal pain is a common presenting complaint in young children and adolescents. The usual cause of musculoskeletal pain is trauma or strain to joint, bone, or muscle. Often, the etiology is never determined, and symptoms resolve with symptomatic treatment. The challenge for the clinician is to rule out serious disease, including infection, as a cause of symptoms. This chapter focuses on the illnesses responsible for three different categories of musculoskeletal symptoms—extremity pain, back pain, and chest pain—and the distinguishing features of each of these illnesses.
Because the differential diagnosis of musculoskeletal pain is extensive, a comprehensive history must be obtained. Important information includes the acuity of onset of illness and presence or absence of fever. Symptoms that are acute, persistent, and accompanied by fever are more likely to be caused by infection. Chronic or subacute symptoms often are the result of noninfectious illnesses.
Important information obtained in the history of the present illness includes the onset and location, description of the progression and severity of the musculoskeletal pain, and whether pain medication has been used and has been helpful. History is elicited of change in gait, ability to bear weight or move the affected area, joint or soft tissue swelling, and presence of induration, erythema, and warmth. A history of trauma, strenuous physical activity, previous or recent illnesses, growth and development, travel, animal or insect exposures, sick contacts, and medication use is important. A review of systems, including history of fever, weight loss, skin or mucous membrane lesions, pharyngitis, eye inflammation, lymphadenopathy, respiratory or cardiac symptoms, abdominal pain, vomiting or diarrhea, recent sexually transmitted diseases, or neurologic symptoms, is crucial in determining whether the musculoskeletal abnormalities are associated with systemic disease. Family history, including history of autoimmune or inflammatory diseases, can be helpful.
The primary focus of the physical examination is on pinpointing the location of symptoms to generate an accurate differential diagnosis and facilitate diagnostic testing. Examination of infants or young children is difficult because they are unable to verbalize the exact location of discomfort. Because musculoskeletal pain can be due to disease affecting a variety of structures, including joints, bones, soft tissues, muscles, nerves, or blood vessels, careful examination of each of these systems is necessary.
Vital signs document the presence or absence of fever, hypothermia, or cardiovascular instability. Height, weight, head circumference, and general appearance of the child should be noted. Poor growth or weight loss could be consistent with inflammatory bowel disease (IBD) or other chronic inflammatory processes, malignancy, or chronic infections such as tuberculosis. Examination of the eyes may reveal conjunctival hyperemia consistent with Kawasaki disease. Mucous membranes are examined for the presence of ulcers (IBD, Behçet disease, systemic lupus erythematosus [SLE]), an enanthem (group A streptococcal infection, enterovirus infection), or hyperemia (Kawasaki disease). Lymphadenopathy can be seen in juvenile idiopathic arthritis (JIA), malignancy, and Kawasaki disease. The chest is palpated for bone tenderness (malignancy, multifocal osteomyelitis, pleurodynia) and for decreased (pleural effusion) and increased (consolidated lung) tactile fremitus during vocalization; the chest is also percussed for dullness (pleural effusion or consolidation). Auscultation can reveal rales, rhonchi, or wheezing (pneumonia associated with hematogenous dissemination of infection to bones, joints, or muscles) or decreased breath sounds such as in pleural effusion (occasionally seen with JIA and SLE). Cardiac examination may reveal a new murmur (endocarditis or acute rheumatic fever [ARF]) or muffled heart sounds (pericarditis). The abdomen should be assessed for tenderness, masses (psoas abscess, tumor), hepatomegaly, or splenomegaly (JIA, malignancy, endocarditis). The skin is evaluated carefully for rash (viral infections, associated bacterial infections or intoxications, Kawasaki disease and other vasculitides).
Careful examination of bones, joints, muscles, and nervous system is particularly important. The examiner should note how the patient holds the affected limb and whether areas of skin or soft tissue appear swollen or red. Gait and stance are observed. The bones and muscles in the affected limb should be palpated, and passive and active range of motion of joints should be evaluated. Pain in the lower extremities can be referred from the back, pelvis, abdomen, or hip. A careful examination of the back and pelvis is necessary to rule out diskitis, vertebral osteomyelitis, pelvic osteomyelitis, or abscess. Bones of the spine and pelvis are palpated, and the spine is assessed for abnormalities in flexion or extension. Skin overlying the vertebral bodies should be examined for the presence of a hemangioma, hair, pit, or mass associated with spinal dysraphism. Infection or structural abnormalities of the hip can cause pain referred to the knee. Examination of the hip joint should be performed in all children with a symptom or sign referable to the lower extremity. Neurologic examination includes evaluation for presence and symmetry of deep tendon reflexes, evaluation for clonus, and sensory examination and estimation of muscle strength. Foot deformities may suggest underlying neurologic conditions.
The laboratory and radiologic evaluation of patients with musculoskeletal pain is guided by findings on history and physical examination. If infection is suspected, attempts should be made to obtain blood cultures and joint, bone, or tissue culture (depending on location of disease) before initiation of antibiotic therapy. Synovial fluid cell count and cultures are recommended, particularly for patients with monoarticular arthritis, fever, and no other sites or signs of systemic disease. A complete blood count (CBC) can be helpful to evaluate for neutrophilia suggestive of infection and inflammatory syndromes, anemia of chronic or systemic disease, thrombocytosis as part of the acute phase response of many inflammatory and infectious syndromes, or thrombocytopenia due to bone marrow suppression of post-viral or oncologic disease. Inflammatory markers (erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP]) can be abnormal with infection, inflammatory disease, and hematologic malignancy. Use of other diagnostic tests depends on the differential diagnosis generated on the basis of the history and physical examination.
If a bone or joint disease is suspected, a plain radiograph of the affected area generally is indicated. Both anteroposterior and lateral views should be obtained because abnormalities sometimes can be missed with a single view. Depending on suspected site of the problem, specialized views sometimes are required ( Fig. 24.1 ). Plain radiographs can identify fracture, chronic bone infection, joint effusion, soft tissue swelling, tumor, and structural abnormalities of bone. Ultrasound is useful in identifying joint effusions, particularly in the hip, although a normal ultrasound does not exclude infectious or inflammatory changes in the joint. MRI may be necessary to diagnose bone infections, particularly in the acute phase and muscle (i.e., myositis) or soft tissue infections. MRI also can be useful to establish the diagnosis and extent of bone involvement of malignancies. Radionuclide bone scan can be useful when multifocal disease is suspected, such as in chronic nonbacterial osteomyelitis (CNO), formerly chronic recurrent multifocal osteomyelitis (CRMO).
The causes of limb pain in children are extensive and include the broad categories of infection, inflammatory disease, malignancy, trauma, and orthopedic problems ( Box 24.1 ). These conditions may involve the joints, bones, muscles, or soft tissue of the affected limb.
Bacterial arthritis
Viral arthritis
Mycoplasma arthritis
Mycobacterial arthritis
Fungal arthritis
Lyme arthritis
Disseminated Neisseria gonorrhoeae
Hepatitis B infection
Subacute bacterial endocarditis
Psoas or obturator internus muscle abscess
Spinal or paraspinal infection
Osteomyelitis
Skin or soft tissue infection
Shingles (varicella zoster)
Acute rheumatic fever
Enteric or sexually transmitted infection
Neisseria meningitidis
Immunization (rubella vaccine, in particular)
Transient (toxic) synovitis
Bone or soft tissue tumors
Leukemia or lymphoma
Metastatic neuroblastoma
Sickle cell anemia
Hemophilia
Juvenile idiopathic arthritis
Systemic lupus erythematosus
Spondyloarthropathy
Dermatomyositis
Henoch-Schönlein purpura
Serum sickness
Kawasaki disease
Trauma
Congenital hip dislocation or dysplasia
Slipped capital femoral epiphysis
Legg-Calvé-Perthes disease
Osgood-Schlatter disease
Chondromalacia patellae
Osteochondritis dissecans
Foreign-body synovitis
Physical overuse syndromes
Inflammatory bowel disease
Reflex sympathetic dystrophy
Familial Mediterranean fever
Behçet disease
Sarcoidosis
Neurologic or neuromuscular disease
Fibromyalgia syndrome
Psychogenic disorders
Arthritis is a common cause of limb pain in children and can have multiple etiologies ( Table 24.1 ). Infection of the joints can be caused by bacterial and, less often, viral or fungal infection.
Etiology | Joints Involved | Associated Findings | Laboratory Studies | Ancillary Studies |
---|---|---|---|---|
Pyogenic arthritis | Any joint, more often joints of lower extremities, usually monoarticular | Fever, joint pain, redness, swelling, decreased range of motion | Elevated WBC, CRP, ESR. Synovial fluid WBC >50,000/μL, predominantly PMN. Blood or joint fluid cultures may be positive | Joint space widening. US shows fluid in joint space |
Transient synovitis | Unilateral hip | Recent viral infection, afebrile or low-grade fever, decreased range of motion of hip joint | CBC <12,000/μL. ESR <40 mm/hr. CRP <2 mg/dL | US shows fluid in joint space, cannot differentiate infected versus noninfected fluid |
Reactive arthritis | Usually large joints of lower extremities, occasionally small joints, wrists, and elbows. Sacroiliac joint involvement in adults | Enteric infection, sexually transmitted diseases, occasionally Streptococcus pyogenes, Neisseria meningitidis. Urethritis, mucous membrane ulcers, conjunctivitis may be present | Elevated ESR, CRP. Synovial fluid WBC <50,000 cells/μL | HLA-B27 positive |
Juvenile idiopathic arthritis | ||||
Systemic | Large or small joints, symmetrically | High fever, evanescent rash, hepatosplenomegaly, lymphadenopathy | Elevated WBC, ESR, and CRP RF and ANAs are negative |
|
Oligoarthritis | Involvement of ≤4 joints within the first 6 mos of illness | Iridocyclitis can be present. | ||
Polyarthritis | Involvement of >4 joints within the first 6 mos of illness | Subdivided into RF-positive and RF-negative forms | ||
Systemic lupus erythematosus | Painful symmetric arthritis involving 2 or more joints, may be migratory | Fever, malar or discoid rash, photosensitivity, oral ulcers, serositis, neurologic abnormalities | Abnormal urinalysis (casts, proteinuria), leukopenia, anemia, thrombocytopenia. Positive anti-DNA or anti-Sm antibody | Radiograph can show pleural effusion ECG can show pericardial effusion |
Acute rheumatic fever | Painful, migratory polyarthritis | Fever, carditis, erythema marginatum, chorea, subcutaneous nodules | Elevated ESR, CRP. Evidence of Streptococcus pyogenes infection (positive culture, ASO titer, or anti-DNase) | Abnormal ECG |
Pyogenic arthritis usually is the result of hematogenous dissemination of bacteria to the joint space and is less likely the result of direct extension from infected bone, soft tissue, or muscle. The usual bacterial causes vary depending on age (see Chapter 77 ); Staphylococcus aureus is the most common cause of pyogenic arthritis in all age groups. Kingella kingae is increasingly recognized as a common cause of pyogenic arthritis in young children (<4 years of age). Pathogens typically causing infection in neonates (e.g., group B Streptococcus and enteric gram-negative organisms) should be considered in infants younger than 2 months. Neisseria gonorrhoeae should be considered in sexually active adolescents. Arthritis caused by Borrelia burgdorferi is considered in children who live in or who have traveled to areas where Lyme disease is endemic. Bacterial arthritis can affect any joint, but the joints of the lower extremity are involved most commonly. Pyogenic arthritis typically is monoarticular, but N. gonorrhoeae and occasionally S. aureus can infect multiple joints. Infants are particularly at risk for infection of multiple joints. Pyogenic arthritis in children is characterized by acute onset of fever, joint pain, redness, and swelling. Physical examination shows markedly decreased range of motion of the affected joint, except in Lyme disease, when effusions characteristically are large and range of motion is relatively preserved.
Pyogenic arthritis of the hip may be difficult to diagnose because associated overlying redness and swelling frequently are not apparent. Pain often is referred to the groin, thigh, or knee. To decrease intracapsular hip joint pressure, the child prefers to hold the affected leg in a flexed, abducted, and externally rotated position. Examination for prone internal rotation is helpful in diagnosing intra-articular hip pathology. The child is placed in a prone position with the pelvis flat on the table and with the knees and ankles flexed and falling away from the body. The examiner tests for pain and limitation of internal rotation. Prompt diagnosis of pyogenic arthritis of the hip is necessary to prevent vascular compromise to the femoral head due to increased intracapsular pressure. Joint effusion can be detected by ultrasonography. If pyogenic hip arthritis is suspected, prompt surgical drainage of infected fluid is indicated.
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